Nutrition and Enhanced Sports Performance

Muscle Building, Endurance, and Strength

Debasis Bagchi, Sreejayan Nair, Chandan K. Sen, Debasis Bagchi, Sreejayan Nair, Chandan K. Sen

• Editorial: Academic Press
• Año: 2013
• ISBN:
  9780123964779
• Categoría: Ciencias biológicas
• Categoría: Anatomía y fisiología humanas

Nutrition and Enhanced Sports Performance: Muscle Building, Endurance, and Strength provides a comprehensive overview to understanding the integrated impact of nutrition on performance. The book is divided into five main themes:

• An introductory overview of the role of nutrition in human health
• Various types of physical exercises, including cardiovascular training, resistance training, aerobic and anaerobic exercise, bioenergetics, and energy balance. This section also covers the nutritional requirements associated with various fitness programs, as well as exercise and nutritional requirements in special populations, including the pre-pubertal, young, elderly, and disabled.
• Sports and nutritional requirements.
• The molecular mechanisms involved in muscle building
• A thorough review of various food, minerals, supplements, phytochemicals, amino acids, transition metals, small molecules and other ergogenic agents that have been implicated in muscle building and human performance

This book is an ideal resource for nutritionists, dietitians, exercise physiologists, health practitioners, researchers, students, athletes, trainers, and all those who wish to broaden their knowledge of nutrition and its role in human performance.

• Discusses the impact of nutrition, including food, minerals, vitamins, hormones, trace elements, etc., that can significantly attenuate/improve human performance and sports
• Addresses the molecular and cellular pathways involved in the physiology of muscle growth and the mechanisms by which nutrients affect muscle health, growth and maintenance
• Encompasses multiple forms of sports/performance and the salient contribution of appropriate nutrition on special populations, including nutritional guidelines and recommendations to athletes
• Strong focus on muscle building

Section 1

Nutrition and Human Health

Outline

Chapter 1 Nutritional Supplementation in Health and Sports Performance

Chapter 2 Glycemic Index, Food Exchange Values and Exercise Performance

Chapter 3 Performance Enhancement Drugs and Sports Supplements for Resistance Training

Chapter 1

Nutritional Supplementation in Health and Sports Performance

Sidney J. Stohs^1,2 and Edeth K. Kitchens², ¹Creighton University Medical Center, Omaha, NB, USA, ²Kitsto Consulting LLC, Frisco, TX, USA

Nutritional status is a major factor in performance and endurance as well as the general health of athletes. Recommendations are provided for vitamins, minerals, omega-3 fatty acids, several amino acids, and protein to assist athletes in achieving optimum nutrition that supports athletic performance. A number of definitions associated with nutritional supplements, as daily values and recommended daily intake, are provided, and the safety of vitamins and minerals is briefly discussed.

Keywords

nutritional supplements; dietary supplements; sports nutrition; vitamins; minerals; omega-3 fatty acids; amino acids; proteins

Introduction

The nutritional status of an athlete is a major determinant of health, fitness and sports performance. Nutrition plays a central role in adaptation, rehydration, refueling, and repair as well as recovery from injury [1–6]. As a consequence, for optimal performance it is essential that athletes be in the best possible nutritional and metabolically balanced state.

Athletes as well as the general population may be overfed and still be deficient in a wide range of essential nutrients including vitamin A, vitamin B₆, vitamin B₁₂, vitamin C, vitamin D, vitamin E, vitamin K, folic acid, iodine, iron, zinc, calcium, magnesium, and selenium [7–13]. These nutritional deficiencies can be extrapolated to athletes, with some indications that the incidence of some deficiencies may be higher among athletes than in the general population. Examples of nutritional deficiencies that have been specifically reported among athletes include iron [1,14], magnesium [14,15], sodium [1,5,16], zinc [1], calcium and vitamin D [17], vitamin C, vitamin E, and vitamin A [18].

The primary reason for nutritional imbalance is consumption of refined foods and dietary supplements that are high in calories from sugars, starches and fats, and low in vitamins, minerals, trace elements and fiber as the result of the refining and manufacturing processes. The net effect is that athletes may consume an excess of calories in conjunction with lower levels of essential nutrients.

At least 85% of athletes and those engaged in regular exercise consume nutritional and dietary supplements on a daily basis [2]. Approximately 50–70% of the adult population consume dietary supplements daily, with women consuming supplements more regularly then men [19]. Other studies indicate that 72% of cardiologists, 59% of dermatologists, 91% of orthopedists and physicians, and 82% of nurses recommended dietary supplements to their patients, while almost 70% of physicians and 89% of nurses at least occasionally used dietary supplements themselves [20,21]. Thus, oral nutrition in the form of dietary supplements is accepted by a large percentage of athletes, the general population, and a wide range of healthcare providers.

Definitions

The US Congress defined the term dietary supplement with the passage of the Dietary Supplement Health and Education Act (DSHEA) of 1994. Therefore, a dietary supplement is defined as a product taken by mouth that contains a “dietary ingredient” intended to supplement the diet. Furthermore, dietary ingredients may include: vitamins, minerals, amino acids, herbs or other botanical products, and substances such as enzymes, glandulars, organ tissues, and metabolites.

Dietary supplements may also be extracts or concentrates, and can occur in forms such as capsules, tablets, powders, liquids, gelcaps, softgels, or bars. They must be labeled as dietary supplements since by law they are a special category of “foods” and not drugs. The definition of dietary supplements used in the USA differs from the definition used in Europe, where the term refers to vitamins and minerals, and herbal products are regulated separately as herbal medicines or herbal remedies [22].

Based on DSHEA, structure /function claims can be made for dietary supplements which describe the role of a dietary ingredient or nutrient that is intended to affect normal structure or function in humans. Several examples of structure/function claims include statements such as “calcium builds strong bones”, “fiber maintains bowel integrity”, “omega-3-fatty acids support heart health”, and “chromium helps maintain blood glucose levels in the normal range”. When a dietary supplement includes a structure/function claim, it must state that the FDA has not evaluated the claim, and must further affirm that the product is not intended to “diagnose, treat, cure or prevent any disease”, since legally only a drug can make these claims.

All nutrition facts panels on labels contain Daily Values (DVs) which represent the recommended daily intake (RDI) of each nutrient that is considered to be adequate to meet the requirements of 97–98% of normal, healthy individuals in all demographics in the United States, based on 2000 kcal per day. RDIs are a reflection of the older Recommended Dietary Allowances (RDAs) which were calculated based on Estimated Average Requirements (EARs) or the amount of a nutrient believed to satisfy the needs of 50% of the people in a demographic. RDA values are usually about 20% higher than EARs. Finally, a system of nutrition recommendations entitled the Dietary Reference Intake (DRI) values was introduced by the Institute of Medicine of the US National Academy of Sciences in 1997 to broaden the RDAs. DRIs have not been widely adopted.

Unfortunately, these multiple systems of recommended essential nutrient intake add much confusion and questionable clarity to the widely asked question “how much of each nutrient is needed for optimal physical performance and health?” In reality, these systems are based largely on the smallest amount of a nutrient needed to prevent a deficiency or disease state, and do not reflect the amount of each nutrient required to provide optimal health and peak physical performance. Furthermore, they project the minimal needs of healthy individuals, with little or no allowance for stressful situations such as intense exercise or disease.

The widely help misconception that only 100% of the DV amount of each essential nutrient is required for good health clearly is not true. Supplementation with a multivitamin/mineral product containing 100% of the DVs may decrease the prevalence of suboptimal levels of some nutrients in athletes, but it will not provide optimal nutritional requirements. Furthermore, providing 100% of the DV for vitamins and minerals does not enhance the levels of various markers of anti-inflammatory activity, antioxidant capacity, or immune response [8,23].

Nutritional Supplement Recommendations for Athletes

Many factors are involved in determining how much of the various essential nutrients are required by an individual to meet daily needs and support optimal sports performance. These factors include: age, weight, gender, stress levels, physical condition, daily physical activity, gastrointestinal health, general health, metabolic rate, disease states, and recovery from injury or surgery. As a consequence, it is apparent that one size (amount) does not fit all, and as previously noted, supplementing with a product that contains 100% of DVs does not adequately meet the overall needs. Metabolism can be equated to a chain which is as strong as its weakest link.

With these considerations in mind, what should be the approximate level of daily intake of nutritional supplements to facilitate optimal performance for an athlete who may be consuming 3000–6000 kcal per day, keeping in mind that DVs are based on a 2000 kcal per day intake? The average athlete should consume dietary supplements daily that contain at least 200–300% of the DVs for vitamins and minerals, and may require 400–600% of the DVs, depending upon the intensity and duration of daily activities. For example, consuming a product with 100% of the DVs for vitamins and minerals two to six times daily or a product with 200–300% of the DVs twice a day with meals may be appropriate.

With respect to optimal nutritional needs, vitamin D is an excellent example of inter-individual variability. In addition to its role in calcium absorption and bone health, vitamin D has been shown to play a role in many other body functions, including immune system support, cognition, cardiovascular health, prevention of some forms of cancer, and blood sugar regulation [24]. The current DV for vitamin D is 400 IU, and many athletes do not meet this minimal requirement [17]. A recommendation by the Institute of Medicine to increase the DV for vitamin D to 600 IU for most adults, based on needs for bone health, has not been adopted by the FDA to date. However, for optimal overall health, blood levels of at least 40 ng/mL of the active intermediate 25-hydroxyvitamin D are recommended, and from 2000 to 4000 IU of vitamin D are needed daily to achieve this level [24].

In order to avoid vitamin A toxicity, vitamin A should be used in the form of beta-carotene or mixed carotenoids and not retinol or its esters retinyl palmitate and retinyl acetate. Beta-carotene is converted into vitamin A as it is needed by the body [25], and exhibits a much greater safety profile.

Vegetarian diets are becoming more popular, and if vitamin B₁₂ supplements are not being used, deficiencies will occur. Low vitamin B₁₂ levels are associated with anemia, lack of endurance, weakness, neurological abnormalities, acidosis, elevated homocysteine levels, decreased HDL levels, and possibly platelet aggregation [26], all of which may contribute to decrements in athletic performance.

Typical multivitamin/mineral supplements do not contain adequate amounts of calcium, magnesium, or vitamin D. Products that contain only vitamin D and calcium with no magnesium are inadequate, and should be avoided. High calcium intake in the absence of magnesium inhibits the absorption of magnesium, and may be one of the reasons for the high incidence of magnesium deficiency in the USA as well as the frequency of leg cramps among athletes and the general public [27,28].

Calcium and magnesium products that are available in chelated and absorbable forms as calcium citrate, fumarate, hydroxyapatite, aspartate or other amino acid chelates [29], and magnesium citrate, ascorbate, aspartate or other amino acid chelate should be used [30,31]. Products that contain magnesium oxide are poorly absorbed and should be avoided [31].

Omega-3 fatty acids are required for normal cell and organ function and are present in every cell in the body. As the result of widespread omega-3-fatty acid deficiency, an estimated 84,000 people die prematurely each year in the USA [32]. In the USA, vegetarians exhibit particularly low intake of this critical nutrient [26]. Omega-3 fatty acids exhibit numerous beneficial functions, including protective effects associated with muscles, joints, cardiovascular system, immune system, brain and nervous system, gastrointestinal system, as well as bones, lungs, liver, skin, eyes, hair, and other organs and tissues [33].

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are the primary omega-3 fatty acids responsible for these health effects. They are derived primarily from fish oils although they ma...